[clang] [analyzer] Moving TaintPropagation checker out of alpha (PR #67352)

[Balazs Benics via cfe-commits]

https://github.com/steakhal commented:

I tried to look at the mentioned 3 TPs, but the links appear to be broken.

Contentwise, I assume its a pure cut-and-paste modulo replacement of `alpha` to `optin`.
I have no objection from moving this checker out of alpha.

https://github.com/llvm/llvm-project/pull/67352